Stoker furnace or heater



Aug. 27, 1940.

F, T. AGRICOLA sToxERFuRNAcE 0R HEATER Fileduarcn 11, 1940 5 Sheets-Sheet Al FREDERIC/T T/QGF/COL/Q BY l ` ATT RNEYS /Nl/ENTR AUS 27. 1940 F..'r. AGRICOLA 2,212,724

STOKER FURNACE OR HEATER Filed March ll, 1940 5 Sheets-Sheet 2 BY7:??1211/2"RICH 7.' AGP/CUL Aug. 27, 1940. l |'='l T AGRlQQLA i 2,212,724

' sTokER FURNACE 0R HEATER Filled March l1, 1940 5 ASheets-Shea?l 5,7.

INVENTOR FREDER/cff r AR/COLA BY y t; AjToRNEY Filed March 1l, 1940 5 Sheets-Sheet l 0 O O O O O O O O O O O O 43 0 O O O O O C- O O O O O O )NVE/V701? FREDERIC/T T GP/COL/Q A T ORNE YS Patented Aug. 27, 1940 UNITED STATES PATENT OFFICE Application March V11,

14 Claims.

My invention has relation to a novel construc tion and arrangement of the fire pot and fuel delivery duct of a Stoker fed furnace or heater.

The object of my invention isv to obtain a more efficient and effective combustion of the fuel and to reduce the heat losses to the stack which result from the present methods of stoker combustion in the furnaces.

The distinctive feature of my invention lies in the introduction of the fuel by a feed stoker so as to form a central mass in the bottom of the fire pot and the introduction of the necessary air for combustion in preheated form only to the marginal edge from the base up of the fuel pile, whereby a zone of intense combustion is maintained from the bottom of the re pot walls upwardly while a relatively cool central zone is maintained through the fire pot and combustion chamber by reason of the fact that no air of combustion is supplied directly to the fuel in the center of the fire pot. By thus concentrating the combustion about the marginal edge of the fuel mass and delivering thereto an ample supply of preheated air, I intensify the combustion against all of the radiating walls of the furnace from the fire pct base up, and suppress or reduce the temperature in the center of the `fire pot and combustion chamber where it would be the least effective since it would pass out more directly to the stack without additionally heating the furnace wall. l

My invention is characterized by introducing an under feed of fuel through an inlet duct which extends up centrally into the re pot and is imperforate so that no air combustion has access to the fuel entering the fire pot. I surround the fire pot wall with a perforate liner which rests below upon a bottom plate having only marginalports for the inflow of the cornbustion air into the annular chamber defined between the fire pot'and the perforate liner, the perforations in the liner admitting air to the marginal edge only of the fuel mass over the inlet duct sogas to induce an intense combustion there while leaving its conter relatively cool. In fact, in the practice of my invention, the intense outer heat penetrating into the fuel mass bringsabout a coking of the latter with a gradual giving off of its more volatile constituent, and these coke masses, responsive to the continued feed of fuel, tend to break apart on radial lines and to scale or lfall oif from the marginal edge of the fuel mass so that there is a continuous delivery of coke into the intense marginal combustion zone 1940, Serial No. 323,272

lying between the fuel feed duct and the perforate liner in the re pot.

My invention will be b est understood by reference to the accompanying drawings which illustrate it in two embodiments, one being for a. standard-heating furnace, and the other for a Stoker fed circulating" heater, but both operate upon the same novel principle above pointed out.

In the drawings:

Fig. 1 is a view of a Stoker furnace, broken away to show the furnace partially in elevation and partially in cross section.

Fig. 2 is a cross sectional View taken on the line II-II of Fig. l.

Fig. v3 is a view in elevation of a circulating heater with its outer casing broken away to show the ash pit and part of the re pot in elevation and the stoker and fuel feed compartments in section. Y

Fig. 4 is a cross sectional view taken on the line IV-IV of Fig. 3.

Fig. 5 is an enlarged vertical cross section taken through the fuel inlet duct and fire pot of the circulating heater.

Fig. 6 is a horizontal sectional view taken on the line VI-VI of Fig. 5.

Fig. '7 is a detail sectional view taken on the line VII- VII of Fig. 6, showing one of the ash and clinked dump doors in an end of the fire pot.

Similar numerals refer to similar parts throughout.

In the embodiment of my invention illustrated in Figs. 1 and 2, I show a conventional type of heating furnace having an outer casing I0, and an ash pit II seated in spaced relation on a base ring I2. The `ash pit I I is closed below by the bottom wall I3 and has a marginal top flange I5 upon which is supported, with a snug fit, the bottom end of the tapered re pot I6. A bottom plate I1, with its marginal edge tapered to conform to the taper of the ilre pot, fits snugly into the lower end of the fire 4pot to close it below except for a central opening, for the reception of the irnperforate-fuel inlet duct I8 and marginal Ports I9 for the admission of air from the ash pit II to the re pot. A tapered perforate liner 20, with its upper'end flared over to abutthe inner Wall of the fire pot I6, rests on the plate l'l with its bottom edge just inside of the series of air ports I 9. This liner is provided with a multiplicity of downwardly directed air jet -ports 2| which extend all around the fire pot and substantially from top to bottom of the liner. The liner thus defines a pre-heating air chamber 22 supplied u through' the ports I9 and which release the air through the ports 2|.

The fuel inlet duct I8 is shaped to be passed down through the central opening in the plate I1 and has a marginal flange 23 which seats on the plate I1 while the walls of the duct below the shoulder fit snugly into the central opening in the plate I1. This heavy shoulder 23 may be cored as shown to lighten the casting, but it will be noted that the delivery end of the duct I8 above the plate I1 is imperforate and flares outwardly and rises approximately midway of the height of the liner 20. Fuel is supplied to the duct I8 through a pipe 25 by a feed screw 26, driven by any suitable mechanism, from any suitable Source of supply and the screw acts to force an under feed of fuel upwardly through the imperforate duct I8 and its delivery end so as to produce a mass or center pile above the bottom within the fire pot. I

The upper end of the fire pot I6 is annular and is flanged to receive the annular base of the ccmbustion chamber 21 which is thus adapted to be turned thereon so as to present its door frome 28 and door 29 in position to face at right angles to the stoker feed pipe 25. The one piece radiator 30'seats on top of the combustion chamber also with an annular fit, and this is provided with the usual radiator clean out collar 3| and clean out door 32. A blower fan 33 delivers air through the pipe 34 into the ash pit under any suitable manual or automatic control, not shown. In like manner the Stoker may have any suitable manual or automatic control for its fuel feed.

In operation, having assembled the'furnace in the manner described and started the feed of fuel and air, as the center of the fuel pile builds up above the delivery and of the duct I8, it forms, in the fire pot I6, a central mass of fuel which has no direct supply of air for combustion eX- cept to its marginal edge and which therefore will not burn freely over its center. As the feed of fuel proceeds, the mass of fuel falls or flakes over from the marginal edge of the pile above the duct I8 and assumes position between the v ange 23 and the liner 20 and there it receives a constant supply of air, preheated by reason of its passage upwardly against the plate I1 and through the annular chamber 22 and the jet ports 2|, and this air is projected downwardly, in a multiplicity of jets against the marginal edge of the fuel pile and produces there a marginal zone of intense combustion against the wall of the liner 2,0 and the re pot I6, and this marginal belt of intensely hot gases flows upwardly along the walls of the combustion chamber, which is generally ribbed for the more enicient radiation of heat to the external air circuit, Yand thence passes into the radiator 30, leaving a relatively lcooler zone maintained through the center of the combustion chamber and re pot. It is my purpose to restrain the combustion at the center of the mass of fuel andato intensify the marginal combustion about this fuel mass. As a result of this I obtain an exceedingly eiiic'ient transfer of heat to the air commencing at the level of the fire pot base and continuing throughout its flow up through the furnace casing I0.

In Figs. 3 to 1 inclusivey-I show my invention applied to what is generally called a circulating heater. As shown this heater comprises a base 40 on which is mounted a cabinet-like casing 4| surrounding and spaced from a heater comprising an ash pit 42, a fire pot 43, and a combustion chamber 44, there being a door 45 in the casing giving access to the combustion chamber. The ash pit is closed below and has an air admission damper 46. In a lateral extension of the casing I form a downwardly tapered fuel chamber 41, with a slopingtop door 48, which chamber delivers the fuel into a shoe 49 where it is engaged by the stoker feed screw 50 and forced through the pipe 5I into the feed duct 52. The pipe 5| is closed at its outer end and screw shaft 50a projects through suitable bearings in the outer `wall 54 of the lateral extension cabinet and is squared so that a crank can be applied and the feed screw turned by hand directly if desired. The preferred manner of operation of the feed screw is to provide a ratchet wheel 55 fast on the screw shaft 53 and placed between the yoke arms at the base of a ratchet arm 56 carrying a pawl 55a engaging the Vratchet 55. A pull lever 58 is attached to the upper end of arm 56 and projects forwardly through the front wall 59 of the stoker extension and is provided with a hand grip by means of which it can be reciprocated to rock the arm 56 back and forth and turn thc stoker feed screw 5D. A coil spring SII normally returns the ratchet arm to retracted position. The feed duct 52 is tapered downwardly and forms a anged half circle cover over the delivery lend of the pipe 5I, the flanges being of such size that they will pass through the central opening in the plate 53 which seats on the lugs 54 at the top of the ash pit 42. The fuel dust is flared as in the construction shown in Fig. l, and seats snugly in the center opening in the bottom plate 43. A perforate liner 6I seats on the plate 53 inwardly from its marginal ports 62 and at its upper edge bears against theV re pot wall, so that it forms a preheating air supply chamber 63 supplied with air by natural or forced draft through the ash pit 42 and ports 62, under control of damper 46, or other suitable air regulating means.

It will be noted, by reference to Fig. 6, that the upper end of the fuel duct 52 is surrounded by a cored downwardly flared flange 64, which at the front and back of the fire pot will rest on the plate 53 adjacent to the base of the liner 6|. Atl the sides of theheater the base `of the flange 64 is substantially spaced from the end walls of the liner and I form clinker cleaner openings 65, each of which receives u rocker door 66 fast on a shaft 61, by means of which the door can be turned to dotted position, Fig. 7, to dump the clinkers and ashes into the ash pit which has a suitable ash door 68. The damper 46 provides for the admission of air through the port 69 and is opened and closed responsive to a manual and automatic control mechanism, such as forms the subject matter of my companion application, Serial No. 191,157, and which comprises the control box 10 containing the thermostat control element. The manual control levers comprise the upright member 1|, the cross shaft 12 and the front hand set '13. The gases of combustion pass off through the stack 14 in the manner well understood and air has access through the base 40 to pass up freely between thc jacket 4| and the heater walls and out through openings in the top of the heater casing.

'I'he operation'of the circulating heater is much the same as that already described, Ythe fuel hopper being filled and the feed screw actuator handle 58 manipulated to feed the fuel up into the re pot and into position to burn marginally responsive to the inow of heated air through the liner 6| in the manner above described. If clinkers or ashes collect in the end zones on the bottom plate 53 they can be removed by actuating a pull rod 'l5 whichprojects through the end of `the wall of the casing and has a common crank connection 16 to each shaft 6l controlling a door 66 and thus both can be rocked at the same time from one end of the casing, it being understood that the cranks 16 are housed withinthe casing.

While I have shown my invention in but two forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and Idesire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

l. A stoker fed furnace comprising a nre pot having a bottom plate with marginal air ports and a center opening, a stoker feed pipe having an imperforate delivery duct passing through said opening and projecting substantially above said bottom plate, a perforated liner surrounding the fire pot wall and adapted to engage the latter overhead and to rest on the bottom plate inwardly f its marginal ports, means to admit a supply of combustion air below said bottom plate for preheated delivery in the combustion chamber only through said perforate liner, and means to feed fuel to said delivery. duct.

2. A stoker furnace according to claim l, in which the perforated area 'of the liner extends from near the bottom plate to a level above said delivery duct. i

3. A stoker furnace according to claim l, in which the delivery duct is formed with an outwardly and downwardly flaring skirt extending from its upper edge into engagement with said bottom plate in spaced relation to said center opening therein. i

A1. A stoker furnace comprising a lower air chamber and a blower air delivery pipe entering I forate fuel delivery duct having a flaring dis'- lil charge end fitted snugly into said center opening and extending upwardly above the same with an outwardly fiared shoulder seated on the upper surface of. said bottom plate, a metallic liner at its upper end engaging `the fire pot walls and at its base resting on said bottom plate and defining a marginal air chamber having communication with said lower air chamber through marginal openings in said bottom plate and having air .delive'ry ports for supplying the preheated air for combustion marginally about the said fire pot, and a combustion chamber surmounting said flre pot and carrying the furnace door and frame.

5. A stoker furnace comprising a lower air chamber having a stoker feed pipe and a blower air delivery pipe entering same, a fire pot mounted on said air chamber and closed below by a bottom plate, an imperforate fuel delivery duct having a flaring discharge end fitted snugly into' downwardly inclined air delivery ports for supplying preheated air for combustion marginally about the said fire pot, anda combustion chamber surmounting said fire pot and carrying the furnace door and frame.

6. A stoker furnace comprising a lower air chamber having a stoker feed pipe and a blower air delivery pipe entering same, a re pot mounted on said air chamber andiclosed below by a bottom plate, an imperforate fuel delivery duct havingv a flaring discharge end fitted snugly into said center opening and extending upwardly above the same with an outwardly flared shoulder seated on the upper surface of said bottom plate, a metallic liner at its upper end engaging the fire pot walls and at its base resting on said bottom plate and defining a marginal air chamber having communication with said lower air chamber through marginal openings in said bottom plate and having downwardly inclined air delivery ports for supplying preheated air for combustion marginally about the said re pot,` and a combustion chamber surmounting said fire pot and carrying the furnace.door and frame and rotatably mounted on said re pot to allow for adjustment of the door in any desired relationship to the fuel and air pipes.

'7. A stoker fed heater comprising an outer t jacket having mounted therein in spaced relation a furnace base, al fire pot mounted on the base, a combustion chamber mounted on the fire pot, a plate forming the bottom of the fire pot and having marginal air ports in communication below with a. source of air supply and having a central fuel opening, a stoker feed pipe for fuel entering said base, an imperforate fuel delivery duct connected to said pipe and fitted into said opening' in the bottom plate and projecting upwardly therethrough to define a flaring imperforate fuel support, a liner defining a narrow and substantially high marginal chamber for preheated air surrounding the walls of said fire pot inwardly of the air ports in said bottom plate, the said liner extending substantially above the delivery nozzle.

8. A stoker fed heater comprising an outer jacket having mounted therein in spaced relation a furnace base, a fire pot mounted on the base,v a combustion chamber mounted on the fire pot, a plate forming the bottom of the fire pot and having marginal air ports in communication below with a source of air supply and having la central fuel opening, 4a stoker feed pipe for fuel entering said base, an imperforate fuel delivery duct connected to said pipe and fitted into said opening in the bottom plate and projecting' upwardlyl therethrough to define av flaring imperforate fuel support, a liner defining la narrow and substantially high marginal chamber for preheated air surrounding the walls of said fire pot inwardly of the air ports in said bottom plate, the said liner extending substantially above the delivery nozzle, said nozzle having a marginal outward fiared apron extending downwardly from its top edge into engagement with said bottom plate to define va downwardly contracted fuel chamber between it and said liner.

9. A stoker fed heater according to claim 7, in which the fire pot is laterally elongated and the flaring base on the delivery duct front and back extends downwardly into substantial juxtaposition to the liner in combination with end clinker discharge doors in the bottom plate between the fire pot end and the ends of said duct.

10. A heater in accordance with claim 7, in

which the. heater jacket is formed at one side with an extension casing including a fuel hopper and a ratchet operating mechanism for the stoker feed screw wit'i means externally operable to actuate said ratchet drive for the feed screw.

11. In a heater having an inner heating unit and an outer jacket surrounding said heating unit, the combination of an extension on one side of said jacket which forms a fuel hopper, a stoker feed mechanism, a second extension on said jacket enclosing said fuel hopper and saidv feed mechanism, a cover for both of said extensions Which when raised permits access to said fuel hopper, and manually operable means extending through said last mentioned extension whereby the stcker feed mechanism may be operated externally of the heater.

12, In a stoker fed heater comprising an inner heating unit having a fire pot and an Y,outer jacket spaced from the heating unit, the combination of a plate forming the bottom in said re pot and having a. central fuel opening and marginal air passages therein, an imperforate fuel delivery duct tted through said opening, a perforated liner seated on said plate and spaced from the fire pot Walls to form a preheating chamber hav- .ing communication below with said marginal ports for a supply of, combustion air, an outturned lip on the top of said liner adapted to engage the fire pot wall with a substantially air tight fit to close said 'preheating chamber at the top, means to admit a regulable air supply beneath said pl'ate, and means to feed fuel through the delivery duct into the center of the fire pot..

13. A heater according to claim 11, in which said manually operable means'cornprise a feed lscrew shaft having a pawl and ratchet drive com- 

